1. Field of the Invention
The present invention relates to a multiple-meter driving apparatus and more particularly to such an apparatus that collectively drives a speedometer, a tachometer, a fuel meter, a water temperature meter and other meters, all of which are used in vehicles such as motorcars and the like.
2. Description of the Related Art
Vehicles such as motorcars and the like use various meters such as a speedometer, a tachometer, a fuel meter, a water temperature meter, an oil pressure meter and so on. These meters are adapted to process a detection signal from the respective one of numerous sensors mounted on an engine, drive shaft, fuel tank or the like and to indicate a physical amount by moving the meter by an angular displacement corresponding to the input. The sensor usually used in the speedometer or tachometer is one that outputs pulse signals having frequencies which are variable depending on the vehicle speed or engine revolution speed. The frequencies in these pulse signals are counted to provide a meter angle signal. On the other hand, the sensor generally used in the fuel meter or oil pressure meter is of such a type that it outputs DC signals having voltage values (or current values) which correspond to the amount of fuel or water temperature level. The DC signals are then converted into digital values which in turn provide meter angle signals. The resulting meter angle signal is applied to two coils Ls and Lc which are disposed perpendicular to each other, as shown in FIG. 1. The coils Ls and Lc then create a magnetic field which in turn rotates a magnet M disposed therein. The magnet M is connected, for example, with a speedometer as shown in FIG. 2. The rotation of the magnet M will cause the angular displacement of the speedometer.
A meter which gives an indication corresponding to the magnitude of electric current applied to two perpendicular coils Ls and Lc is called a "cross-coil meter".
The conventional meter driving devices which provide meter indications based on pulse and DC signals from the respective sensors comprise a processor or controller for processing the detection signals from the sensors corresponding to the speedometer, tachometer, fuel meter, water temperature meter and other meters.
There are thus problems in that as the number of meters to be mounted in a vehicle-increases, the corresponding number of driving devices must be mounted in the vehicle, thereby increasing the necessary space and also the manufacturing cost.